In many fire emergency vehicles the operation or effectiveness of the vehicle depends on members of a crew being in proper position. Particularly in the case of double-drive vehicles, it is important that the tillerman be in position for steering the rear end of the vehicle. In other fire vehicles such as pumpers, it is important that the vehicle not leave until fire-fighters are in place on the rear platform provided thereon. Also, in modular vehicles, such as ambulances, the driver cannot see whether the crew members are located within the main body portion thereof.
While various interlock systems have heretofore been developed to prevent an automotive engine from being started if a seat belt is not fastened such systems are not readily adaptable to the purposes of the present invention.